Perhaps you should try some spelling variations:
trinh viet » ninh viet, trinh vat
dinh viet » ninh viet, danh viet, sinh vien
toc sach » hoc sach, doc sach, thuoc sach
cua tre » cua te, cuu tre, cua triet
sach ty » sach y, sach tu, sach thu
xang ma » tang ma, nang ma, sang ma
ve cac » vien cac
ma hoi » mai hoi, xa hoi, ma hoa

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ty xang ma hoi. hieu ((ve cac) or (va cac)) duc va ((dinh viet) OR (trinh viet)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty xang ma hoi. hieu ((ve cac) OR (va cac)) duc va ((dinh viet) OR (trinh viet)) cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty xang ma hoi. hieu ((ve cac) or (va cac)) duc va ((dinh viet) OR (trinh viet)) cua tre*".